UI support for TimeTravel Debugging

src/vs/workbench/parts/debug/browser/debugActionsWidget.ts

@@ -31,6 +31,7 @@ export class DebugActionsWidget implements wbext.IWorkbenchContribution {
 	private actions: actions.IAction[];
 	private pauseAction: dbgactions.PauseAction;
 	private continueAction: dbgactions.ContinueAction;
+	private stepBackAction: dbgactions.StepBackDebugAction;
 	private isVisible: boolean;
 	private isBuilt: boolean;
 
@@ -120,10 +121,22 @@ export class DebugActionsWidget implements wbext.IWorkbenchContribution {
 				this.toDispose.push(a);
 			});
 			this.toDispose.push(this.pauseAction);
+			this.toDispose.push(this.continueAction);
 		}
 		this.actions[0] = state === debug.State.Running ? this.pauseAction : this.continueAction;
 
-		return this.actions;
+		const activeSession = this.debugService.getActiveSession();
+		if (activeSession && activeSession.configuration.capabilities.supportsStepBack) {
+			if (!this.stepBackAction) {
+				this.stepBackAction = instantiationService.createInstance(dbgactions.StepBackDebugAction, dbgactions.StepBackDebugAction.ID, dbgactions.StepBackDebugAction.LABEL);
+				this.toDispose.push(this.stepBackAction);
+			}
+
+			// Return a copy of this.actions containing stepBackAction
+			return [...this.actions.slice(0, 4), this.stepBackAction, ...this.actions.slice(4)];
+		} else {
+			return this.actions;
+		}
 	}
 
 	public dispose(): void {

src/vs/workbench/parts/debug/browser/media/debug.contribution.css

@@ -86,6 +86,11 @@
 	background: url('step-out.svg') center center no-repeat;
 }
 
+.monaco-workbench .debug-action.step-back {
+	background: url('step-over.svg') center center no-repeat;
+	transform: scaleX(-1);
+}
+
 .monaco-workbench .debug-action.continue {
 	background: url('continue.svg') center center no-repeat;
 }
@@ -280,6 +285,11 @@
 	background: url('step-out-inverse.svg') center center no-repeat;
 }
 
+.vs-dark .monaco-workbench .debug-action.step-back {
+	background: url('step-over-inverse.svg') center center no-repeat;
+	transform: scaleX(-1);
+}
+
 .vs-dark .monaco-workbench .debug-action.continue {
 	background: url('continue-inverse.svg') center center no-repeat;
 }
@@ -340,6 +350,11 @@
 	background: url('step-out-inverse.svg') center center no-repeat;
 }
 
+.hc-black .monaco-workbench .debug-action.step-back {
+	background: url('step-over-inverse.svg') center center no-repeat;
+	transform: scaleX(-1);
+}
+
 .hc-black .monaco-workbench .debug-action.continue {
 	background: url('continue-inverse.svg') center center no-repeat;
 }

src/vs/workbench/parts/debug/common/debug.ts

@@ -411,6 +411,7 @@ export interface IDebugService {
 	next(threadId: number): TPromise<void>;
 	stepIn(threadId: number): TPromise<void>;
 	stepOut(threadId: number): TPromise<void>;
+	stepBack(threadId: number): TPromise<void>;
 	continue(threadId: number): TPromise<void>;
 	pause(threadId: number): TPromise<any>;
 }

src/vs/workbench/parts/debug/electron-browser/debug.contribution.ts

@@ -105,6 +105,7 @@ registry.registerWorkbenchAction(new SyncActionDescriptor(
 registry.registerWorkbenchAction(new SyncActionDescriptor(dbgactions.StepOverDebugAction, dbgactions.StepOverDebugAction.ID, dbgactions.StepOverDebugAction.LABEL, { primary: KeyCode.F10 }, KbExpr.has(debug.CONTEXT_IN_DEBUG_MODE)), 'Debug: Step Over', debugCategory);
 registry.registerWorkbenchAction(new SyncActionDescriptor(dbgactions.StepIntoDebugAction, dbgactions.StepIntoDebugAction.ID, dbgactions.StepIntoDebugAction.LABEL, { primary: KeyCode.F11 }, KbExpr.has(debug.CONTEXT_IN_DEBUG_MODE), KeybindingsRegistry.WEIGHT.workbenchContrib(1)), 'Debug: Step Into', debugCategory);
 registry.registerWorkbenchAction(new SyncActionDescriptor(dbgactions.StepOutDebugAction, dbgactions.StepOutDebugAction.ID, dbgactions.StepOutDebugAction.LABEL, { primary: KeyMod.Shift | KeyCode.F11 }, KbExpr.has(debug.CONTEXT_IN_DEBUG_MODE)), 'Debug: Step Out', debugCategory);
+registry.registerWorkbenchAction(new SyncActionDescriptor(dbgactions.StepBackDebugAction, dbgactions.StepBackDebugAction.ID, dbgactions.StepBackDebugAction.LABEL, { primary: KeyMod.Shift | KeyCode.F10 }, KbExpr.has(debug.CONTEXT_IN_DEBUG_MODE)), 'Debug: Step Back', debugCategory);
 registry.registerWorkbenchAction(new SyncActionDescriptor(dbgactions.RestartDebugAction, dbgactions.RestartDebugAction.ID, dbgactions.RestartDebugAction.LABEL, { primary: KeyMod.Shift | KeyMod.CtrlCmd | KeyCode.F5 }, KbExpr.has(debug.CONTEXT_IN_DEBUG_MODE)), 'Debug: Restart', debugCategory);
 registry.registerWorkbenchAction(new SyncActionDescriptor(dbgactions.StopDebugAction, dbgactions.StopDebugAction.ID, dbgactions.StopDebugAction.LABEL, { primary: KeyMod.Shift | KeyCode.F5 }, KbExpr.has(debug.CONTEXT_IN_DEBUG_MODE)), 'Debug: Stop', debugCategory);
 registry.registerWorkbenchAction(new SyncActionDescriptor(dbgactions.ContinueAction, dbgactions.ContinueAction.ID, dbgactions.ContinueAction.LABEL, { primary: KeyCode.F5 }, KbExpr.has(debug.CONTEXT_IN_DEBUG_MODE)), 'Debug: Continue', debugCategory);

src/vs/workbench/parts/debug/electron-browser/debugActions.ts

@@ -218,6 +218,28 @@ export class StepOutDebugAction extends AbstractDebugAction {
 	}
 }
 
+export class StepBackDebugAction extends AbstractDebugAction {
+	static ID = 'workbench.action.debug.stepBack';
+	static LABEL = nls.localize('stepBackDebug', "Step Back");
+
+	constructor(id: string, label: string, @IDebugService debugService: IDebugService, @IKeybindingService keybindingService: IKeybindingService) {
+		super(id, label, 'debug-action step-back', debugService, keybindingService);
+	}
+
+	public run(thread: debug.IThread): TPromise<any> {
+		const threadId = thread && thread instanceof model.Thread ? thread.threadId
+			: this.debugService.getViewModel().getFocusedThreadId();
+
+		return this.debugService.stepBack(threadId);
+	}
+
+	protected isEnabled(state: debug.State): boolean {
+		const activeSession = this.debugService.getActiveSession();
+		return super.isEnabled(state) && state === debug.State.Stopped &&
+			activeSession && activeSession.configuration.capabilities.supportsStepBack;
+	}
+}
+
 export class StopDebugAction extends AbstractDebugAction {
 	static ID = 'workbench.action.debug.stop';
 	static LABEL = nls.localize('stopDebug', "Stop");

src/vs/workbench/parts/debug/electron-browser/debugService.ts

@@ -872,6 +872,16 @@ export class DebugService implements debug.IDebugService {
 		});
 	}
 
+	public stepBack(threadId: number): TPromise<void> {
+		if (!this.session) {
+			return TPromise.as(null);
+		}
+
+		return this.session.stepBack({ threadId }).then(() => {
+			this.lazyTransitionToRunningState(threadId);
+		});
+	}
+
 	public continue(threadId: number): TPromise<void> {
 		if (!this.session) {
 			return TPromise.as(null);

src/vs/workbench/parts/debug/node/rawDebugSession.ts

@@ -234,6 +234,10 @@ export class RawDebugSession extends v8.V8Protocol implements debug.IRawDebugSes
 		return this.send('stepOut', args);
 	}
 
+	public stepBack(args: DebugProtocol.StepBackArguments): TPromise<DebugProtocol.StepBackResponse> {
+		return this.send('stepBack', args);
+	}
+
 	public continue(args: DebugProtocol.ContinueArguments): TPromise<DebugProtocol.ContinueResponse> {
 		return this.send('continue', args);
 	}

src/vs/workbench/parts/debug/test/common/mockDebugService.ts

@@ -115,6 +115,10 @@ export class MockDebugService implements debug.IDebugService {
 		return TPromise.as(null);
 	}
 
+	public stepBack(threadId: number): TPromise<void> {
+		return TPromise.as(null);
+	}
+
 	public continue(threadId: number): TPromise<void> {
 		return TPromise.as(null);
 	}